1. Field of the Invention
The invention relates to a fan device, more particularly to a heat-dissipating fan device.
2. Description of the Related Art
FIG. 1 illustrates a conventional heat-dissipating fan device 1 that includes a fan housing 10 and a fan impeller 12. The fan housing 10 has a top wall 13 formed with an inlet 131, a bottom wall 14, and a side wall 11 transverse to the top and bottom walls 13, 14 and formed with an outlet 111. The top, bottom and side walls 13, 14, 11 confine a receiving space 15. The fan impeller 12 is mounted in the receiving space 14 of the fan housing 10.
Referring to FIGS. 2 to 4, the fan impeller 12 includes a hub cap 121, a plurality of coupling ribs 122, a first connecting ring 125, a second connecting ring 124, and a plurality of fan blades 123. The hub cap 121 has opposite upper and lower portions 1211, 1212. The coupling ribs 122 extend radially and outwardly from the lower portion 1212 of the hub cap 121 (see FIG. 4), and are spaced apart angularly from each other (see FIG. 3). The first connecting ring 125 is disposed coaxially around the lower portion 1212 of the hub cap 121, and is connected to the coupling ribs 122. The second connecting ring 124 is disposed coaxially around the upper portion 1211 of the hub cap 121. The fan blades 123 are spaced apart angularly from each other (see FIG. 3). Each fan blade 123 extends radially, and is connected to and is disposed uprightly on the first connecting ring 125. Each fan blade 123 has an outer lateral edge connected to the second connecting ring 124. As such, rotation of the fan impeller 12 draws air to flow from the inlet 131 of the fan housing 10 toward the outlet 111 of the fan housing 10.
However, during rotation of the fan impeller 12, air drawn into the receiving space 15 initially flows downwardly toward the bottom wall 14 of the fan housing 10, and is subsequently directed to flow radially toward the outlet 111 of the fan housing 10 such that the conventional heat-dissipating device 1 cannot generate a stable airflow amount as a result of airflow disturbance in the receiving space 15 of the fan housing 10. Furthermore, the second connecting ring 124 obstructs airflow through the outlet 111.